The effect of thyroid autoantibodies on dyslipidemia in patients with mild form of subclinical hypothyroidism

Introduction: Increased incidence of dyslipidemia was found in patients with subclinical hypothyroidism
(ScH) with positive anti-TPO antibodies. However, there are no studies which evaluate the effect of
thyroid substitution therapy on lipids in these patients.
Aim: To evaluate the effect of the presence of anti-TPO antibodies on lipid parameters in patients with
mild form of ScH treated with levothyroxine.
Materials and methods: Fifty-seven patients with newly diagnosed subclinical hypothyroidism (ScH) and
thyroid-stimulating hormone (TSH) levels below 10 mIU/L, who met the treatment criteria, were included
in the study. Lipid parameters and anti-TPO antibodies were evaluated at the first visit and only lipids
after 5 months euthyroid stage.
Results. The average value of TSH in patients was 8.1 ± 1.9 mIU/L. The euthyroid state was achieved
with a mean dose of 60.8 ± 19 μg in a mean durat ion of 7.5 ± 2.2 months. Thyroid substitution therapy
significantly decreased total cholesterol and LDL-C, and increased HDL-C. TSH positively correlated with
total cholesterol (r = 0.147, p < 0.05), and FT4 statistically significantly positively correlated with HDLC
(r = 0.197, p < 0.05). The lipid parameters did not respond to L-T4 treatment in patients with negative
anti-TPO antibodies, while a decrease in total cholesterol, total cholesterol/HDL-C, and LDL-C/HDL-C was
observed in patients with positive anti-TPO antibodies.
Conclusion: Patients with mild ScH and positive anti-TPO antibodies with high cholesterol levels may
benefit from thyroid substitution therapy.
Keywords: subclinical hypothyroidism, dyslipidemia, thyroid autoantibodies, thyroid substitution therapy